A variety of natural and semisynthetic complex carbohydrates or polysaccharides have been commercially important in human and pet food manufacturing; in the cosmetic, paper, textile, paint, agricultural, explosives, hydrolube, adhesive, ceramic, cleaning polish, detergent, fire fighting, ink, photography, lithography, and deodorant gel industries; and in mining, and gas well drilling and production. Natural complex carbohydrates and polysaccharides include seaweed extracts, plant exudates, seed or root extracts, and microbial polysaccharides produced by fermentation. Semisynthetic complex carbohydrates and polysaccharides include cellulose derivatives, low-methoxyl pectin, propylene glycol alginate, triethanolamine alginate and guar gum derivatives. Sandford, P. & Baird, J. (1983) "Industrial Utilization of Polysaccharides" in The Polysaccharides, Vol. 2, pp. 411-491.
The production of natural complex carbohydrates or polysaccharides is frequently problematic. For plant exudates and seed or root extracts, production is dependent on climate and harvest conditions. For example, gum arabic is an exudate from Acacia senegal trees. Gum production is stimulated by stripping the bark from the trees; the gum is collected by hand in the form of "dried tears." Production of gum arabic can vary each year as a function of weather conditions, labor strikes, natural disasters, etc. Meer et al. (1975) Food Technology 29:22-30. The unreliable supply results in variable gum arabic cost. Seed gums, such as guar gums are expensive due to harvesting costs. Guar gum is derived from the seed of the guar plant Cyamopsis tetragonolobus. Processing involves removal of the seed coat, separation of the germ from the endosperm, and milling of the endosperm. Sandford, P. & Baird, J. (1983), supra. Further, gums obtained from such sources may have variable quality and exhibit variable functional properties.
The production of seaweed extracts can also be problematic. Agar production is labor intensive in that it involves the harvesting of red seaweed by hand: in some areas of the world, divers in full pressure suits collect individual plants in deep water; in other places, the seaweed can be collected at low tide without the use of diving equipment. Carrageenan or Irish Moss is produced from another red seaweed harvested by raking and hand gathering. Algin is produced from brown algae which can be harvested manually or with small mechanical harvesters. Sandford, P. & Baird, J. (1983), supra.
Further, hand harvesting can introduce a purity problem. For example, hand collected lots of gum arabic are seldom pure; samples are classified according to grade which depends on color, and contamination with foreign bodies such as wood or bark (VanNostrand's Scientific Encyclopedia, 7th ed. (1989) D. Considine (ed.), Vol. I, p. 1389).
Microbial fermentation gums such as xanthan gum avoid many of the difficulties associated with harvesting of plant exudates or extraction of algae because production is carried out in fermentation facilities. However, xanthan gum production poses other problems. Xanthan gum is produced by Xanthamonas campestris, which presents a cell disposal problem because X. campestris is a plant pathogen (Scaad, N. W. (1982) Plant Disease 66(10):882-890). Xanthan gum has also been objected to as being too expensive for certain applications such as drilling mud. See, e.g., Kirk-Othmer Chemical Engineering Encyclopedia (3rd. ed. 1981) 17:153.
Thus, there is a clear need in a number of industries for a reliable, relatively inexpensive gum or class of gums that do not create a disposal problem. While a number of plant cells have been observed to produce polysaccharide and/or complex carbohydrates when cultured (Aspinall, G. & Molloy, J. (1969) Canadian J. Biochem. 47:1063-1070; Fincher, G. et al. (1983) Ann. Rev. Plant Physiol. 34:47-70; Clarke, A. et al. (1979) 18:521-540; McNeil, M. et al. (1984) Ann. Rev. Biochem. 53:625-663; Hale, A. et al. (1987) Plant Cell Reports 6:435-438; and Bacic, A. et al. (1987) Australian J. Plant Physiol. 14:633-641), it has not been suggested that such cultured plant cell gums might be suitable in the pharmaceutical, paper, textile, paint, agricultural, explosives, hydrolube, adhesive, ceramic, cleaning polish, detergent, fire fighting, ink, photography and lithography industries; or in mining, and oil and gas well drilling and production. Only Otsuji, K. et al. EP 0 285 829 (published Oct. 12, 1988) have utilized cultured Polianthus gum in cosmetic applications.
Related work by the inventors hereof has been published in WO 8806627 (1988) and WO 9402113 (1994). WO 8806627 relates in general to the use of cultured plant cell gums in the manufacture of food products as emulsifiers, thickening agents, gelling agents and the like. Cultured plant cell gums of Pyrus, Prunus, and Rosa are specifically exemplified. U.S. Pat. No. 5,133,979 (issued Jul. 28, 1992) and U.S. Pat. No. 5,296,245 (issued Mar. 22, 1994) are directed to similar subject matter. WO 9402113 relates to the general use of cultured plant cell gums as emulsifiers, viscosifiers, and the like for the manufacture of industrial, pharmaceutical or cosmetic products. Cultured plant cell gums from suspension cultures of Nicotiana, Pyrus, Phleum and Lolium are exemplified.